Effects of 1.8 GHz Radiofrequency Fields on the Emotional Behavior and Spatial Memory of Adolescent Mice

Abstract

Effects of 1.8 GHz Radiofrequency Fields on the Emotional Behavior and Spatial Memory of Adolescent Mice Zhang JP, Zhang KY, Guo L, Chen QL, Gao P, Wang T, Li J, Guo GZ, Ding GR. Effects of 1.8 GHz Radiofrequency Fields on the Emotional Behavior and Spatial Memory of Adolescent Mice. Int J Environ Res Public Health. 2017 Nov 5;14(11). pii: E1344. doi: 10.3390/ijerph14111344. Abstract The increasing use of mobile phones by teenagers has raised concern about the cognitive effects of radiofrequency (RF) fields. In this study, we investigated the effects of 4-week exposure to a 1.8 GHz RF field on the emotional behavior and spatial memory of adolescent male mice. Anxiety-like behavior was evaluated by open field test (OFT) and elevated plus maze (EPM) test, while depression-like behavior was evaluated by sucrose preference test (SPT), tail suspension test (TST) and forced swim test (FST). The spatial learning and memory ability were evaluated by Morris water maze (MWM) experiments. The levels of amino acid neurotransmitters were determined by liquid chromatography-mass spectrometry (LC-MS). The histology of the brain was examined by hematoxylin-eosin (HE) staining. It was found that the depression-like behavior, spatial memory ability and histology of the brain did not change obviously after RF exposure. However, the anxiety-like behavior increased in mice, while, the levels of γ-aminobutyric acid (GABA) and aspartic acid (Asp) in cortex and hippocampus significantly decreased after RF exposure. These data suggested that RF exposure under these conditions do not affect the depression-like behavior, spatial memory and brain histology in adolescent male mice, but it may however increase the level of anxiety, and GABA and Asp were probably involved in this effect. Note: The 1.8 GHz frequency field was not modulated like cellphone radiation. Excerpts Mice were exposed to 1.8 GHz frequency field for 28 days, 6 h/day (9:00 AM to 3:00 PM). During exposure, the animals had access to food and water. The SAR of whole body and brain were approximately 2.7 W/kg and 2.2 W/kg at a distance of 1 m from the antenna. Since the incidence and polarization of free movement mice kept changing during exposure, the deviation between the average SAR value and the maximum and the minimum of SAR was about 8%. The power density in this study was 530 μW/cm2 ... It was found that exposure to 2.70 W/kg RF field did not obviously affect the surface body temperature of mice (Figure 1), which suggested that no gross thermal effects were involved. Additionally, the air temperature of the exposure cage with a temperature hygrometer was measured and the results showed that air temperature difference did not exceed 0.1 °C during 6 h exposure. Effects of RF Exposure on Anxiety-Like Behaviors The anxiety-like behaviors of mice were evaluated by OFT and EPM after RF exposure. OFT results showed that there were no significant differences in accumulative total distance traveled between the sham group and RF group (Figure 2a). However, the accumulative distance in the center area and the time spent in the central area decreased significantly in the RF group, compared with the sham group (Figure 2b,c), which indicated that 4- week RF exposure could increase the animals' anxiety-like behavior. In addition, EPM results showed that there were no significant differences in the number of total entries into the arms between the sham group and RF group, which indicated that the locomotor activity in the mice did not change after RF exposure (Figure 3a). However, the percentage of the total time spent in the open arms and the percentage of the entries into the open arms decreased significantly in the RF group, compared with the sham group (Figure 3b,c). These results were consistent with that of OFT. It was reported that GABA in mice brain, plays a key role in the modulation of anxiety response [40,41,42,43], and in this study, we found that the level of GABA in mice brain decreased significantly after RF exposure. Considering the OFT and EPM results, we speculated that the GABA probably was involved in RF induce anxiety in mice. Additionally, it was found that the level of Asp in mice brain significantly changed after RF exposure. Regarding the relationship between the behavior and Asp remains unclear. In the present study, brain SAR 2.2 W/kg was selected based on the 2.0 W/kg limit by the International Commission on Nonionizing Radiation Protection (ICNIRP) and Institute of Electrical and Electronics Engineers (IEEE) [44,45]. It was found that after 6 h RF field exposure, the temperature of mice surface body did not change obviously compared with sham group, which suggested that no gross thermal effects were involved in RF-induced anxiety behavior in mice. Conclusions 4-week exposure to 1.8 GHz RF field had no significant effect on depression-like behavior, spatial learning and memory ability or the histology of brain in adolescent male mice. However, it may increase the level of anxiety, and amino acid neurotransmitters such as GABA might be involved. Open Access Paper: mdpi.com

AI evidence extraction

Main findings

After 4-week exposure to a 1.8 GHz RF field (brain SAR ~2.2 W/kg; whole-body SAR ~2.7 W/kg), depression-like behavior, spatial learning/memory, and brain histology were reported as not obviously changed versus sham. Anxiety-like behavior increased on OFT and EPM, and GABA and aspartic acid levels in cortex and hippocampus significantly decreased after RF exposure; no gross thermal effects were observed based on body surface temperature and cage air temperature measurements.

Outcomes measured

• Anxiety-like behavior (open field test; elevated plus maze)
• Depression-like behavior (sucrose preference; tail suspension; forced swim)
• Spatial learning and memory (Morris water maze)
• Amino acid neurotransmitters in cortex and hippocampus (LC-MS; GABA, aspartic acid)
• Brain histology (hematoxylin-eosin staining)
• Body surface temperature / thermal effects

Limitations

• Sample size not reported in provided text
• Exposure described as not modulated like cellphone radiation (limits direct applicability to typical mobile-phone signals)

Suggested hubs

• who-icnirp (0.55)
  Abstract/excerpts explicitly reference ICNIRP (and IEEE) SAR limits as rationale for exposure level.

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    "population": "Adolescent male mice",
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